🌳 Outdoor LoRa-GPS tracker with E-Ink display 🔑

power 18650
wireless LoRa,
sensor GPS, E-Ink
mcu SAMD21G18
bom items 82
bom cost USD $78.93
vendors 6
completed July 2022

Power overview

Power source

4200mAh 18650 button-top battery

Battery life

14 hours

Charging duration

14 hours
Just plug in the USB cable to the Oak PCB that has the 18650 battery in the holder at the back. RED Charging LED will light up when charging. The battery will be fully charged when the RED Charging LED turns off.

Charging the battery

The multimeter with data logging feature was hooked up to the test points of VBAT and GND. It took about 11 hours to fully charge the battery with the on-board charging circuit.

Charging Setup

Charging Setup

Charging graph

Measuring battery life

Two types of firmware was uploaded to measure the longest possible and shortest possible battery life:

  1. Longest possible: Blinky LED was 19 hours
  2. Shortest possible: Demo was 14 hours

Charging Setup

Charging Setup

Example of a discharging graph